For an overwhelmingly Christian country which prides itself on freedom of expression, removing "offensive" Christmas trees and censoring school Santas may seem curious.

Santas are fine as long as they do not proselytise in schools

But as far as American public institutions are concerned, it is not Christmas but the "holiday season".

Any school, public library, university or government building which at this time of year crosses the constitutional boundary between church and state - be it simply through singing Silent Night or erecting a
nativity scene on the lawn - risks being the target of a lawsuit.

The supporters of such campaigns believe they are necessary to ensure the US, founded by those fleeing political persecution, does not exclude anyone on the basis of their faith - particularly amid post-9/11 religious tensions.

But for others, both within the religious right and beyond it, the joy of Christmas is being eroded by a group of politically-correct lobbyists who are turning another great American cause - freedom
- on its head with a particularly joyless form of censorship.

Contentious candy

The constitution, as successive supreme court rulings have proved, does not exclude religion from schools.

A nativity scene can be displayed provided it is within a cultural context - that is to say featuring symbols from other religions as part of a secular display of peoples' differing beliefs, while students themselves are allowed to pray and preach within school parameters almost to their hearts' content.

It was recently ruled that a high school was wrong to exclude pupils for distributing Christmas sweets featuring a religious message, as it violated their freedom of speech.

But had their teachers, as
representatives of the state, given out such candy to their charges, it would have been a different story.

Most Orthodox Jews certainly wouldn't get upset by a Christmas tree - it's not viewed as an offensive religious symbol

Nathan DiamentOrthodox Union

The Kansas branch of the American Civil Liberties Union (ACLU) has, for example, just issued a complaint over a "sneaky Santa", a man who was invited into several state schools by the local authorities and who allegedly used his time there to "proselytise".

After asking the children what the meaning of Christmas was, one or two youngsters apparently offered the information that it was connected to the birth of Jesus, with which the Santa concurred.

"He was sneaky. He took advantage of his access to children to preach, and that simply cannot be allowed to happen," said Dick Kurtenbach of the Kansas ACLU, which has made a complaint.

A professor, similarly upset by a Christmas tree in the hall of the law school at Indiana University, successfully campaigned for its removal earlier this month.

Professor Florence Wagman Roisman's stated aim was in part to make sure the university remained an inclusive area in which no-one felt offended or left out.

The tree is now gone, replaced by a "winter scene" whose main feature is snow and a sleigh - some of the few unoffending articles that remain. "It's very pretty," an eyewitness told BBC News Online. "I don't think anyone can get upset by this."

Offended?

Whether Christmas trees, or a Santa suggesting that Christmas is connected with the birth of Christ, do in fact cause offence in America to non-Christians, is a moot point.

I objected to the official display of the Christmas tree because it is a symbol of one religion, Christianity

Florence Wagman RoismanIndiana University

The Christmas tree has for many lost its religious meaning over the decades.

In addition, even the most secular members of society, and those of other beliefs, concur that Christmas is inextricably linked to the tale of Christ's alleged birth - whether one believes in the virgin birth or not.

"We take a very accommodationist view towards all
this," says Nathan Diament of the Union of Orthodox Jewish Congregations of America, the nation's largest orthodox Jewish umbrella organisation.

"And most Orthodox Jews certainly wouldn't get upset by a Christmas tree - it's not viewed as an offensive religious symbol."

Some ardent defenders of the distinction between church and state also believe that the pursuit of Christmas trees and Santas is unwarranted.

"This is really taking it too far," says Susan Jacoby, author of the forthcoming Freethinkers: A History of American Secularism. "People really don't see Christmas trees in that light."

"But that is certainly not to say that keeping religious symbols from schools is not an important objective. You have to look at this in the context of the existing fears over the influence of Christianity in the public arena, and particularly in schools."

The continuing row over evolution - which has led some schools to slap disclaimer stickers to biology textbooks warning that evolution is a theory rather than a fact - is viewed as one such example of Christian sway in the US.

Meanwhile the multi-million-dollar funding for abstinence only sex education in schools is also believed to have been inspired, at least in part, by the president's own religious convictions.

Nativity no-no

Nonetheless, Christian justice groups still perceive that their religion is under threat from left-wingers and secular thinkers who want to wipe Christianity from the American map.

This year they are throwing their support behind a Catholic New York mother, who is suing the city's school authorities over their failure to include a Christian symbol in a seasonal display which included the Jewish menorah and an Islamic crescent.

The authorities are apparently arguing that the Jewish and Islamic symbols are "historical", but a nativity scene is not. A request by BBC News Online for further explanation met no response.

"We don't believe there's a constitutional problem with displaying such religious symbols in the public school context," says Jay Sekulow, chief counsel of the American Center for Law and Justice, which represents Christians in church-state cases.

"The problem is when one symbol - in this case the Christian symbol - is excluded. In our view, that is unfair treatment and the type of hostility that violates the constitutional protections we enjoy as Americans."

The secular Susan Jacoby also agrees that it is wrong to exclude the nativity scene when other religions are represented. But she draws a different conclusion.

"This just goes to show that there should be no room for religious symbolism in our schools. Someone's bound to get left out, there will always be an angry mother."

The row is likely to continue well into the New Year, and will resurface next Christmas too. And the one after that.